This invention relates to connecting optical fiber sections and more particularly to optical fiber coupling apparatus providing pressure sealing at an optical joint having high pressure cryogenic media on one side of the joint and ambient conditions on the other side, the coupling permitting transmission of signals through two or more discrete optical channels.
Optical fiber connectors are used for connecting two or more optical fibers in such a way that the optical signal may pass from one fiber to another at a joint therebetween. The transmission of information in the form of optical signals has increased greatly but the quality of the coupling between the fiber segments is critical to the quality of the transmission of the signals through the joint. Consequently, contact and precise alignment between the optical components is important to minimize the attenuation of the optical signal at the connection.
Although pressure tolerant couplings are known in the prior art for use in underwater applications where the pressure is the same on both sides, as disclosed in Morency et al. U.S. Pat. No. 4,432,603, and in underwater applications through a bulkhead having a high pressure differential wall, such as disclosed in Cowen et al., U.S. Pat. No. 4,469,399, and in applications where a probe is used for measuring temperature molten plastic or metal under high pressure, such as disclosed in Dostoomian et al., U.S. Pat. No. 4,444,516, a problem which has not been addressed by the prior art is that of coupling optical fibers not only where there is a high pressure differential across the coupling joint, but also where one end of the probe must be physically located at the high pressure and at extremely low temperatures. This problem is presented for instrumentation probe feedthrough applications relating to the space program. For example, a fiber optic probe is utilized for a bearing deflectometer to obtain data relating to the high pressure oxidizer turbopump utilized in the space shuttle main engine. Pressurized oxygen at cryogenic temperatures and pressures of approximately 600 lbs. per square inch are presented at the measuring end of the probe for monitoring by instrumentation located at ambient pressure.